The invention relates to compressors. More particularly, the invention relates to sound and vibration suppression in screw-type compressors.
In positive displacement compressors, discrete volumes of gas are: trapped at a suction pressure; compressed; and discharged at a discharge pressure. The trapping and discharge each may produce pressure pulsations and related noise generation. Accordingly, a well developed field exists in compressor sound suppression.
One class of absorptive mufflers involves passing the refrigerant flow discharged from the compressor working elements through an annular space between inner and outer annular layers of sound absorptive material (e.g., fiber batting or foam). U.S. Pat. No. 6,799,657 B2 discloses a basic such muffler and then improved versions having integral helmholtz resonators formed within the inner layer. The disclosure of this '657 patent is incorporated by reference herein as if set forth at length.
Commonly owned and concurrently filed U.S. patent application Ser. No. 10/956,509, now abandoned, entitled Compressor Sound Suppression discloses a discharge plenum centerbody and methods for configuring such a centerbody. The disclosure of that application is incorporated by reference herein as if set forth at length.